Pulmonary changes in 7,000 mice following prolonged exposure to ambient and filtered Los Angeles air.

Abstract

This report summarizes the incidence and appearance of lung tumors and pneumonitis in over 7,000 mice, following prolonged exposure to ambient as compared with filtered Los Angeles air. Mice in the ambient air colonies showed no difference in histologic appearance and no increase in incidence of lung tumors in two lung tumor susceptible and one lung tumor resistant strains; on the contrary, more lung adenomas in A/J mice were noted in the filtered air group. Acute bronchopneumonia and interstitial pneumonitis were qualitatively similar but quantitatively significantly more common in ambient air C57 black mice. The findings suggest that prolonged exposure to ambient Los Angeles air is associated in several strains of mice with an increased susceptibility to pulmonary infection but not to increased pulmonary neoplasia.